Graphical user interface for a portion of a display screen



FIG. 1 is a front view of a graphical user interface for a portion of a display screen showing my new design; and,

FIG. 2 is a front view of a second embodiment thereof.

The broken line showings of a portion of a display screen and graphical elements within the display screen form no part of the claimed design. 

The ornamental design for a graphical user interface for a portion of a display screen, as shown and described. 